Hypohalogenation of tetramethyl and tetraethyl methylenediphosphonates and trihydrocarbyl phosphonoacetates

ABSTRACT

The process of reacting either (1) a tetraalkyl (methyl, ethyl, halomethyl or haloethyl) methylenediphosphonate or (2) a trihydrocarbyl (C2-C4) phosphonoacetate with a hypohalite in an aqueous electrolyte solution (preferably in the presence of an inert, water-immiscible, organic solvent) to produce the corresponding mono- and di-halogenated methylenediphosphonate and phosphonoacetate esters. These esters have utility as intermediates in the synthesis of detergent builders and as extreme pressure additives for lubricant compositions.

United States Patent [72] Inventor John Downing Curry Oxford, Ohio [21 1Appl. No. 770,805

[22] Filed Oct. 25, 1968 [45] Patented Nov. 30, 197 l [7 3] Assignee TheProctor & Gamble Company Cincinnati, Ohio Continuation-impart ofapplication Ser. No; 624,226, Mar. 20, 1967, now abandonedContinuation-impart of application Ser. No. 717,999, Apr. 1, 1968, nowabandoned. This application Oct. 25, 1968, Ser. No. 770,805

[ 54] HYPOHALOGENATION OF TETRAMETHYL AND TETRAETHYLMETHYLENEDIPHOSPHONATES AND TRIHYDROCARBYL PHOSPHONOACETATES 10 Claims,No Drawings [52] U.S. Cl 260/986, 252/499, 260/932, 260/941, 260/969[51] Int. Cl C07f 9/40 [50] Field of Search... 260/932, 986

[56] References Cited UNITED STATES PATENTS 3,299,123 1/1967 Fitch et a1260/932 X 3,422,021 1/1969 Roy 260/932 X 3,471,552 10/1969 Budnick260/932 X OTHER REFERENCES Groggins, Unit Processes ln OrganicChemistry, McGraw- Hill New York, Fifth Edition (1958), pages 206 to 208and 250.

Bunyan et al., Journal Of The Chemical Society (London) (1962) pp. 2953to 2958 (London) (1962) Primary Examiner-Alex Mazel AssistantExaminerRichard L. Raymond AllorneysRichard C. Witte and Robert B. AylorHYPOHALOGENATION F TETRAMETHYL AND TETRAETHYL METHYLENEDIPHOSPHONA'IESAND TRIHYDROCARBYL PHOSPI-IONOACETATES CROSS-REFERENCE This applicationis a continuation-in-part of copending U.S. applications Ser. Nos.624,226, filed Mar. 20, 1967 and 717,999 filed Apr. 1, 1968 and both nowabandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to a process for the production of monoand dihalogenatedgem-diphosphonate esters and phosphonoacetate esters. It relatesspecifically to a process for the production of monoand dihalogenatedtetramethyl and tetraethyl methylenediphosphonates and trihydrocarbylphosphonoacetates which are valuable intermediates in the syntheses ofdetergent builders and as extreme pressure additives for lubricantcompositions. The use of builders as adjuncts to soap and syntheticdetergents and the properties demonstrated by their use in improvingdetergency levels is well known. Such gem-diphosphonate esters arehereinafter and such referred to as methylenediphosphonatesphosphonoacetate esters are referred to as phosphonoacetates.

The use of the halogenated methylenediphosphonates and halogenatedphosphonoacetates as extreme pressure additives for lubricantcompositions is disclosed in the copending application of Robert EarlWarm, Denzel Allan Nicholson and Ted Joe Logan, Ser. No. 762,966, filedSept. 26, 1968, entitled Lubricant Composition."

Among the satisfactory builders that can be obtained from the compoundsof this invention are the alkali metal, ammonium, or substitutedammonium salt forms of substituted methylenediphosphonic acid compoundsderived from the halogenated methylenediphosphonate esters. The use andpreparation of such salts using the compounds prepared by this inventionis more fully described in U.S. Pat. No. 3,422,021 issued Jan. 14, 1969,and U.S. Pat. No. 3,404,178 issued Oct. 1, 1968. The disclosures thereofare hereby incorporated by reference. The halogenated tetramethyl andtetraethyl methylenediphosphonates produced by the process of thisinvention are stated, in the Roy application, to be converted to theircorresponding builder salts by several methods. An example of one suchpreparation is the hydrolysis of tetraethyl methylenediphosphonate esterwith refluxing I-ICl to produce the free phosphonic acid, and then, theaddition of base such as NaOH to the acid producing the correspondingbuilder salt. 1

The use of salts derived from methylenediphosphonate esters as buildershas not until recently been of substantial interest. Therefore, verylittle literature is available as to their use as builders and evenlesser amounts regarding the preparation of halogenatedmethylenediphosphonate esters. Nevertheless, there are several methodsof replacing an active hydrogen by halogenation, old in the art, bywhich halogenated tetramethyl and tetraethyl methylenediphosphonatesmight conceivably be synthesized. However, reactions such as directhalogenation of either tetramethyl or tetraethyl esters ofmethylenediphosphonic acid or their carbanion have proved to be limitedin yield and often involve side reactions hampering the completion ofthe esired reaction. These reactions have been found to be impracticalas they are expensive and require elevated temperatures. Suchhalogenation methods seldom result in yields of monoor dihalogenatedmethylenediphosphonate esters greater than about 25 percent.

2. Description of Prior Art The copending U.S. application, Ser. No.587,417 of Quimby et al., filed Oct. 18, 1966, and now abandonedpresents a practical process for the production of halogenatedtetraalkyl methylenediphosphonates which minimizes the difficultiesencountered in halogenating methylenediphosphonate esters.

This application discloses a high-yield process for the hypohalogenationof tetraalkyl methylenediphosphonates having alkyl radicals containingthree to about eight carbon atoms. This process involves a two-phasereaction system comprising (a) an aqueous hypohalite solution containingelectrolyte, and (b).,an immiscible methylenediphosphonate ester phase.Due to the high degree of solubility in water and aqueous electrolytesolutions of tetraaikyl methylenediphosphonates having alkyl radicalscontaining less than three carbon atoms, this process is not useful inhalogenating these specific short alkyl chain methylenediphosphonateesters in sufficiently high yields to make it attractive. There is,therefore, a need for a process by which such methylenediphosphonateesters can be halogenated.

It has been discovered that by employing the process of this invention,satisfactory yields of halogenated methylenediphosphonates andphosphonoacetates can be obtained. This process is capable of beingdirected largely towards producing either the monoor dihalo derivativesof these methylenediphosphonates and phosphonoacetates. The mechanismsby which the process can be so directed will be discussed andillustrated below.

The entire scope of applicability of the invention will become apparentfrom the detailed description give hereinafter.

SUMMARY OF THE INVENTION It has now been discovered that halogenatedmethylenedisphosphonates and halogenated phosphonoacetates are preparedby a process which comprises the steps of reacting, with vigorousstirring, a compound selected from the group consisting of: (l) amethylenediphosphonate having the formula R PO Cl'l Po R in which each Ris selected from the group consisting of methyl, ethyl, halomethyl andhaloethyl radicals and (2) a phosphonoacetate, having the formula R 'POCI-l C00R' wherein each R is selected from the group consisting ofalkyl, alkenyl, haloalkyl, and haloalkenyl radicals containing from twoto four carbon atoms, with a hypohalite ion selected from the groupconsisting of 0C1, OBr, and OI, the molar proportions of the reactantscorresponding to one mole of said methylenediphosphonate orphosphonoacetate to from about 0.75 to about 6.0 moles of saidhypohalite ion in a reaction mixture comprising (a) an aqueouselectrolyte solution containing from 4.0 to about 65 percent electrolyteby weight, and preferably (b) an inert water-immiscible organic solventin which the halogenated methylenediphosphonates and halogenatedphosphonoacetates are soluble to at least 5 percent by weight, thetemperature of the reaction being in the range of from 0 to C., the pHof the aqueous solution being greater than about 7 and the reaction timebeing from about 1 minute to about 2.0 hours.

DETAILED DISCLOSURE The present invention is valuable in that thereactants and the reaction conditions mentioned above can be adjusted inthe manner outlined and exemplified below to produce unexpectedly highyields of monoand dihalo-derivatives of the methylenediphosphonates andphosphonoacetates.

For instance, if the starting methylenediphosphonate reactant is eithertetramethyl methylenediphosphonate or tetraethyl methylenediphosphonate,the reaction product is either a monohalogenated tetramethylmethylenediphosphonate, or a dihalogenated tetramethylmethylenediphosphonate, a monohalogenated tetraethylmethylenediphosphonate or a dihalogenated tetraethylmethylenediphosphonate depending on the reaction conditions employedwithin the ranges specified above. Thus, by the present invention, theprocess can be used to prepare such compounds as tetramethylmonochloromethylenediphosphonate, tetramethylmonobromomethylenediphosphonate, tetramethylmonoiodomethylenediphosphonate, tetramethyldichloromethylenediphosphonate, tetra( difluoromethyl)dichloromethylenediphosphonate, tetramethyldibromomethylenediphosphonate, tetramethyl diiodomethylenediphosphonate,tetraethyl monochloromethylenediphosphonate, tetraethylmonobromomethylenediphosphonate, tetraethylrnonoiodomethylenediphosphonate, tetraethyldichloromethylenediphosphonate, tetraethyldibromomethylenediphosphonate, dimethyl diethyldibromomethylenediphosphonate, methyl triethylbromoiodomethylenediphosphonate and tetraethyldiiodomethylenediphosphonate.

1f the starting phosphonoacetate reactant is either triisopropylphosphonoacetate, tripropyl phosphonoacetate, triethyl phosphonoacetate,tributyl phosphonoacetate or triisobutyl phosphonoacetate, the reactionproduct is either a monohalogenated or a dihalogenated trialkylphosphonoacetate. Thus, by the present invention the process can be usedto prepare such compounds as triethyl monochlorophosphonoacetate,triethyl monobromophosphonoacetate, triethyl monoiodophosphonoacetate,triethyl diiodophosphonoacetate, triisopropyl dibromophosphonoacetate,triisopropyl diiodophosphonoacetate, triisopropyldichlorophosphonoacetate, tributyl monobromophosphonoacetate, tributyldiehlorophosphonoacetate, tributyl diiodophosphonoacetate, ethylisopropyl isobutyl dibromophosphonoacetate, tributenyldibromophosphonoacetate, tri(2-chloroethyl) diiodophosphonoacetate, tri(3-iodopropenyl) diiodophosphonoacetate and 2,3-dibromopropyl dimethyldibromophosphonoacetate.

The reaction system is a fairly complex one, but by adhering to theconditions set forth above and more fully explained in the followingdiscussion, highyields of any of the foregoing compounds can beprepared.

The embodiment of this invention according to which amonohalomethylenediphosphonate is prepared is illustrated by thefollowing equation:

The embodiment of this invention according to which amonohalophosphonoacetate is prepared is illustrated by the followingequation:

In the above equations OX represents a hypohalite ion with X being ahalogen atom selected from the group consisting of chlorine, bromine,and iodine atoms, M is an electrolyte not containing a halide X that canbe displaced by the OX used; S is an inert, water-immiscible, organicsolvent, if one is employed; R is selected from the group consisting ofmethyl, ethyl, halomethyl and haloethyl; and R is selected from thegroup consisting of alkyl, alkenyl, haloalkyl and haloalkenyl radicalscontaining from two to four carbon atoms.

For purposes of understanding the present invention, the hypohalitereactant is depicted simply as OX1 rather than as an inorganichypohalite compound. It is to be understood that the essential reactionmoiety is the hypohalite ion. lt can either be introduced as aninorganic hypohalite such as NaOBr, NaOCl, NaOl, or other equivalentalkali metal and alkaline earth metal forms. Alternatively, thehypohalite ion can be generated in situ by means described below.

It has now been discovered that surprisingly high yields of amonohalogenated product can be obtained using from about 0.75 to about1.10 moles of hypohalite to one mole of methylenediphosphonate orphosphonoacetate. It is preferred, for maximum yields that from about0.95 to about 1.10 moles of hypohalite ion to one mole of eithermethylenediphosphonate or phosphonoacetate be employed. It is importantthat no more than about 1.10 moles of hypohalite per mole ofmethylenediphosphonate or phosphonoacetate be present in the abovereaction in order to prepare high yields of a monohalogenated compound.A larger portion of hypohalite ion tends to carry the reaction on toform the dihalo methylenediphosphonates or phosphonoacetates asexplained below. The reactions of equations 1 and [I can be terminated,as discussed hereinafter, producing surprisingly high yields of monohalomethylenediphosphonates or phosphonoacetates.

According to a further embodiment of this invention, the above reactioncan be allowed to continue, producing the corresponding dihalomethylenediphosphonates or phosphonoacetates. In this embodiment of theinvention, the hypohalite ion reacts with the monohalo reaction productof equations l and Il to produce the corresponding dihalomethylenediphosphonates or phosphonoacetates. To provide sufiicienthypohalite ion to form dihalo ester compounds, a large excess ofhypohalite ion should be used. It has been discovered that the highestyield of dihalo methylenediphosphonate or phosphonoacetate is obtainedby using from about 2.0 to about 6 moles of hypohalite ion per one moleof methylenediphosphonate or phosphonoacetate. It is preferred that from2.05 to about 2.10 moles of hypohalite ion be used per one mole ofmethylenediphosphonate or phosphonoacetate in the foregoing reaction tofavor formation of the dihalo methylenediphosphonates orphosphonoacetates.

The dihalogenation embodiment of the present invention is more fullyillustrated in the following equations wherein all terms are as definedin equations I and 11. Equation 11] can be considered in conjunctionwith equation I above in which the XCl-l(PO R2)2 starting material isthoughtof as the reaction product of equation l and equation N can beconsidered in conjunction with equation ll above in which the R' PO CXH-COOR starting material is thought of as the reaction product of equationII.

By the same token, the preparation of the dihalo esters can proceedaccording to the equation 111 or equation IV reaction sequences bybeginning with a monohalo methylenediphosphonate or phosphonoacetateobtained from any source, i.e., from equations l or II or from any othersuitable reactions. It will be appreciated that when this approach istaken, the two X's need not be the same. In this latter event, highestyields of dihalo methylenediphosphonate or phosphonoacetate are obtainedby using from about 1 to about 3 moles of hypohalite ion per 1 mole ofmonohalo methylenediphosphonate or phosphonoacetate, and preferably fromabout 1.05 to about 1.10 moles of hypohalite ion per 1 mole of monohalomethylenediphosphonate or phosphonoacetate in the foregoing reactionsIll and IV.

When the highly preferred method of using anorganic solvent is employed,(in the case of the phosphonoacetates this highly preferred embodimentis required for good yields). the halogenation reactions of thisinvention are heterogeneous reactions between two substantiallyimmiscible liquid phases, viz, an organic phase and an aqueouselectrolyte phase.

Using an inert organic solvent is not a critical aspect of thisinvention. Some of the halogenated tetramethyl and tetraethylmethylenediphosphonates are obtained when large proportions ofelectrolyte are used even without the addition of an inert organicsolvent as illustrated in example Vl; however, the use of an inertorganic phase solvent is highly preferred, primarily because of overallprocess efficiency, i.e. less time need be consumed and in someinstances lower levels of electrolyte can be employed.

The preferred organic phase is comprised of an inert, waterimmiscible,organic solvent in which the halogenated methylenediphosphonates and/orphosphonoacetates are solubleand which is neither halogenated bynoroxidizedby the hypohalite and does not react with base at the reactionconditions. To be suitable for use in the process of this invention, theinert organic solvent must be capable of dissolving the halogenatedmethylenediphosphonate and/or phosphonoacetate reaction products to atleast 5 percent by weight of the solvent.

Examples of organic materials which can be used generally in the processof this invention include benzene, trichlorobenzene, and ethers.Preferred organic solvents suitable for use in this invention arepolyhalogenated materials such as chloroform, carbon tetrachloride andsymtetrachloroethane. The inert organic materials most preferred for usein the process of this invention are halogenated compounds such ascarbon tetrachloride.

The aqueous electrolyte phase is considered the reaction zone and itshould have an electrolyte concentration of from about 4.0 to about 65percent by weight. The exact electrolyte concentration can varythroughout this range and will depend on the specific reaction beingpracticed. However, when preparing tetramethyldihalomethylenediphosphonates and trihydrocarbyl dihalophosphonoacetatesit is preferred that from about to about 65 percent by weight ofelectrolyte be employed. This range is preferred when preparingtetramethyl dihalomethylenediphosphonates because if amounts ofelectrolyte substantially less than percent by weight are employed, thecorresponding product yield is substantially reduced.

The electrolyte for use in thisprocess can be a compound selected fromthe general class known as electrolytes which are water soluble to atleast 5.0 percentby weight. More specifically, the electrolytes for usein theaqueous phase can be a water-soluble inorganic base such as NaOHor KO; or a water-soluble inorganic salt which will notreact when thehypohalite which is used, such as NaCl, Na CO NaNO K CO Kl, Na,SO,, K 80NaOOCCll and the like or any other compounds of the general class knownas electrolytes which are water soluble and which will not react withthe hypohalite, e.g., the alkali metal borates, carboxylates, andphosphates. Care must be taken that the electrolyte chosen is not a saltof a halide other than that which is being reacted with themethylenediphosphonate or phosphonoacetate. if this care is not taken,substitution of halides other than that desired halide which is beingreacted with the methylenediphosphonate or phosphonoacetate could occuras a competing reaction.

The reactions set forth in equations l-lV must be conducted above a pHof 7 at a temperature of from about 0 to about 75 C. These reactionstake from about I minute to about 2 hours depending upon the rate ofaddition of reactants, temperature and general reaction conditions. inthe preferred embodiment of the present invention, themethylenediphosphonate or phosphonoacetate is added to a mixture of theaqueous electrolyte phase and the inert organic solvent and is stirredvigorously. Vigorous stirring breaks the organic phase into tinydiscrete globules intermixed with the aqueous phase. This agitation ofthe mixture is continued, while adding to the reaction mixture eitherOCl', OBr or Ol.

It is important in directing the process of the present invention towardthe monohalide product (equations 1 and II) that the hypohalite be addedto the methylenediphosphonate or phosphonoacetate in order to minimizeany excess of hypohalite present during the reaction. While theforegoing represents the preferred method of adding reactants in theprocess of the present invention, the hypohalite can be generated in theaqueous phase subsequent to the addition of the methylenediphosphonateor phosphonoacetate or the methylenediphosphonate or phosphonoacetate orthe methylenediphosphonate or phosphonoacetate can be added rapidly tothe hypohalite.

The reactant hypohalite ion can be added directly to an aqueous solutionor can be generated in situ such as, for example, by repeated additionsof small amounts of the desired halogen such as liquid bromine, chlorinegas, or iodine as a solid or solution. Suitable hypohalites which can beadded directly include all alkali metal and alkaline earthhypochlorites, hypobromites and hypoiodites. Examples of suitablehypohalite compounds include CalOClh; Ca(OBr),, KOCI, KOBr, NaOCI, andNaOBr. It is preferred that the hypohalite ion be generated in situ forreasons stated hereinafter.

Generally, the solubility of the methylenediphosphonate and/orphosphonoacetate in the aqueous electrolyte solution can besubstantially controlled, i.e., increased or decreased, by decreasing orincreasing the electrolyte concentration, respectively. The greater theelectrolyte concentration in the aqueous solution, the lower is thesolubility of the methylenediphosphonate and phosphonoacetate reactantsin the aqueous solution. The reverse is also true, that is, the lowerthe electrolyte concentration the greater the solubility of thesereactants. The solubility of the methylenediphosphonates and/orphosphonoacetates in the aqueous reaction electrolyte solution can alsobe increased or decreased by increasing or decreasing the temperature,respectively.

Generally, whether the reaction product is the monohalo or dihaloderivative of a methylenediphosphonate or phosphonoacetate is controlledby the proportion of the hypohalite reactant employed. If the desiredend product is the monohalogenated derivative, from about 0.75 to aboutl.l0 moles of hypohalite ion per 1 mole of methylenediphosphonate orphosphonoacetate, should be used. For maximum yields of the monohalideit is preferred that from about 0.95 to about 1.10 moles of hypohaliteion per mole of methylenediphosphonate or phosphonoacetate be employed.Amounts of hypohalite greater than about l.l0 moles per mole ofmethylenediphosphonate or phosphonoacetate tend to favor the formationof increasing amounts of dihalogenated product.

Recovery of the halogenated methylenediphosphonate and phosphonoacetateproducts from the organic solvent, if one is employed, can be performedby cessation of stirring which allows the aggregation of tiny discreteinert organic phase globules containing the halogenatedmethylenediphosphonate or phosphonoacetate. The inert organic phasecontaining the halogenated methylenediphosphonates or phosphonoacetatescan then be readily separated from the aqueous solution by conventionaldecanting methods, and the halogenated methylenediphosphonates orphosphonoacetates extracted from the inert organic material by methodsold in the art, e.g., column chromatography, selective extraction,distillation or fractional crystallization.

At extreme conditions, e.g., 6 moles of hypohalite ion per mole ofmethylenediphosphonate or phosphonoacetate reactant and 75 C., thealkenyl esters can react further with the hypohalite to form halohydrinsby known reactions. Therefore, in general, these extreme conditionsshould be avoided when alkenyl esters are used.

In practicing each of the foregoing embodiments of this invention caremust be taken that the reaction temperatures are not so high that thehypohalite ion (OX) is converted to the halate ion (XOf) creating adeficiency of hypohalite ion in the reaction mixture. For example,temperatures up to about 50 C. are usually satisfactory for theavoidance of hypochlorite conversion, but are only marginallysatisfactory for hypobromite conversion avoidance. However, bygenerating the hypohalite in situ the reactions can be conducted atsubstantially higher temperatures, i.e., over C., as the hypohalite ionreacts with the methylenediphosphonate or phosphonoacetate before thereis time for it to disproportionate to from halate ion.

The temperature must not be so high that it reaches a point at whichundesirable ester saponification becomes significant. The temperature atwhich saponification occurs is governed by the pH of the system that isbeing used, higher pH favoring more saponification. Ester saponificationto a significantly detrimental degree will occur above about 75 C. whenthe pH of the system is near neutrality, i.e., from about pH 7 to aboutpH 9. However, at highly basic pHs saponification will occur to adetrimental degree at lower temperatures. if an organic solvent isemployed, the temperature cannot be higher than the boiling point of theinert organic solvent as the solvent would be lost from the reactionsystem. For example, the boiling point of carbon tetrachloride is 77 C.,and the boiling point of chloroform is 61 C.

Care must be taken to avoid excessive formation of hypohalous acid inthe reaction system. The aqueous reaction medium must be kept basicenough to sustain the desired hypohalite ion. If the pH of the reactionsystem drops below about 7 the equilibrium HOX-tlOX+H*will shift to theleft, causing the hypohalite ion to disappear. Consequently, the pH ofthe reaction system must be kept above about 7 in the case of chlorineaddition, and should be above about a pH of 8 for bromine addition andabove a pH of 10 for iodine addition. The reaction for each halide maybe conducted with a pH as high as about 14 and it is preferable that thepH of the reaction solution be above about 1 1.

The tetraalkyl methylenediphosphonates used as starting materials inthis invention can be prepared by reacting dibromomethane with atrialkyl phosphite in accordance with the following equation:

wherein R is an alkyl radical selected from the group consisting ofmethyl and ethyl. The trialkyl phosphite in this reaction can be derivedfrom a primary alcohol and phosphorus trichloride. The dibromomethane isa high temperature reaction product of methane and bromine. A moredetailed discussion of the foregoing appears in US. Pat. No. 3,251,907of Clarence H. Roy, issued May 17, 1966. Trialkyl phosphonoacetates canbe prepared as follows: P(OR) ClCH CoOR'i R 'PO -CH -COOR+R'Cl or theycanbe purchased commercially.

The compounds of this invention have the formula k PO CXPO R whereineach R is selected from the group consisting of methyl, ethyl,halomethyl and haloethyl radicals, one X is selected from the groupconsisting of bromine and iodine atoms and the other X is selected fromthe group consisting of chlorine, bromine and iodine atoms. Thesecompounds are effective extreme pressure additives for lubricantcompositions as disclosed in the copending application of Robert EarlWann, Denzel Allan Nicholson and Ted Joe Logan, Ser. No. 762,966, filedSept. 26, 1968 entitled Lubricant Composition. As disclosed in thatapplication, the bromo and iodo derivatives of themethylenediphosphonate esters are more effective extreme pressureadditives than the corresponding chloro derivatives. Preferably, both Xsare either iodine or bromine atoms. This application is incorporatedherein by reference.

The process of this invention is illustrated by the followin examplesbut is not limited thereto.

EXAMPLE 1 Tetraethyl Monobromomethylenediphosphonate An aqueouselectrolyte solution was prepared by adding 8.55 g. (.0535 mole) ofbromine to an 18 percent sodium hydroxide (30 g.) aqueous solution at 10C. in a 250 ml. glass beaker. This produced about 0.05 mole of NaOBr andan electrolyte concentration dictated by the amount of bromine and NaOH.The pH of the solution was about 13.5 fifty milliliters of CC], wasadded to this solution forming a two-phase system. The mixture was thencooled to about 6 C.

While stirring the. mixture vigorously with a magnetic stirring device,14.4 g. (0.05 mole) of tetraethyl methylenediphosphonate was added tothe two-phase system. After allowing the mixture to react for about 5minutes, the organic phase was separated from the mixture using aseparatory funnel. Then, CC], was separated from the ester reactionproduct by using a flash evaporator (the organic phase is placed in aheated rotating vessel to which an aspirator is attached causing avacuum which distills off CCL).

Using anuclear magnetic resonance spectrometer, a P nmr analysis wasmade indicating 48 percent of the product was tetraethylmonobromomethylenediphosphonate, 10 percent was tetraethyldibromomethylenediphosphonate and 42 percent was unreacted tetraethylmethylenediphosphonate. The monobromomethylenediphosphonate ester can beseparated from the reaction product by fractional crystallization.Results similar to the foregoing can be obtained if the pH is maintainedabout 1 1.

EXAMPLE ll Tetraethyl Monobromomethylenediphosphonate All the steps inexample I were repeated using the same equipment and reactants; however,in this example the electrolyte concentration of the aqueous phase wasincreased by adding 20 g. of K CO to the aqueous phase. Additionallyseveral milliliters of H 0 were added. This produced an initialelectrolyte concentration of about 35 percent (based on K CO After thereaction was complete and the product separated from the mixture, a Pnmr analysis revealed that 60 percent of the product was tetraethylmonobromomethylenediphosphonate, l5 percent was tetraethyldibromomethylenediphosphonate, and the remaining 25 percent wasunreacted tetraethyl methylenediphosphonate.

Results similar to those in the foregoing examples can be obtained usingmany other electrolytes, e.g., NaOH, KOH, Na CO and N aNO Also, similarresults can be obtained if the CCL, organic solvent is replaced bychloroform or sym-tetrachloroethane.

Similarly, tetramethyl methylenedisphosphonate could be employed in theforegoing examples replacing tetraethyl methylenedisphosphonateproducing a predominately tetramethyl monobromomethylenediphosphonateproduct and NaOCl or NaOI could be employed, replacing NaOBr, to producepredominantly tetramethyl monochloroor monoidomethylenediphosphonateproduct.

EXAMPLE Ill Tetramethyl Dichloromethylenediphosphonate Three hundred andfifty grams of K CO were dissolved in 510 g. of an aqueous solutioncontaining 5.25 percent NaOCl and 4.1 percent NaCl in a 2-liter glassbeaker. The final solution had a pH of 13.5 and an electrolyteconcentration of about 41 percent (based on K CO This solution containsabout 0.36 moles of hypochlorite. To this solution, 200 ml. of CHCl wasadded forming a two-phase system. The total system was then cooled to 10C.

15.0 g. (0.065 mole) of tetramethyl methylenediphosphonate was added,with vigorous stirring, to the two-phase system. After 10 minutes, theorganic layer was removed from the aqueous layer with a separatoryfunnel and was, thereafter, washed with water. CHCl was then removedfrom the organic phase by flash evaporation. A P nmr analysis on theresidue showed that 93 percent of the material was tetramethyldichloromethylenediphosphonate. The weight of the residue was 19.4grams.

Results similar to the foregoing can be obtained if the organic solventemployed is carbon tetrachloride or symtetrachloroethane.

EXAMPLE IV Tetraethyl Dichloromethylenediphosphonate An aqueouselectrolyte solution (2,120 g.) containing 5.25 percent NaOCl and 4.1percent NaCl which contained 1.5 moles of hypochlorite and had a pH ofabout 1 1.5 and an electrolyte concentration due only to the sodiumchloride was mixed in a 3 liter glass beaker with 800 ml. of Cl-lCl toform a two-phase system. To this two-phase system, cooled to 12 C., wasadded 100 g. (0.35 moles) of tetraethyl methylenediphosphonate, whilestirring vigorously. After about 20 minutes the Cl-lCl layer (organicphase) was separated and the CHCl removed by flash evaporation. Ananalysis by P nmr indicated that 92 percent of the product wastetraethyl dichloromethylenediphosphonate. The distilled (in vacuo)ester was obtained in a 76 percent yield.

EXAMPLE V Tetraethyl Dibromomethylenediphosphonate Two hundred and fiftyml. of CCl was mixed in a 2-liter glass beaker with an aqueouselectrolyte solution consisting of 0.94 moles of bromine and 468 g. of a18 percent NaOl-l solution. This formed a two-phase system which wasthen cooled to 5 C. The aqueous electrolyte phase had an electrolyteconcentration dictated by the amount of bromine and NaOH and a pH ofabout 13.7. It also contained 0.94 moles of hypobromite.

At this point 100 g. (0.35 moles) of tetraethyl methylenediphosphonatewas added with stirring to the twophase system. After addition of theester, the ice bath was removed and the mixture stirred for minutes. Thelayers were then separated and the CCl layer (organic phase) was washedseveral times with water. The CCL was then removed from the ester byflash evaporation. P nmr analysis indicated that the crude product was95 percent tetraethyl dibromomethylenediphosphonate. Distillation (invacuo) gave the desired product at a 66 percent yield.

EXAMPLE V1 Tetraethyl Dichloromethylenediphosphonate An aqueouselectrolyte solution (1,500 g.) containing 5.25 percent NaOCl 1.06moles) and 4.1 percent NaCl was mixed with 1,000 g. K CO in a 3-literglass beaker. The electrolyte concentration was about 40 percent (basedon K CO giving a pH of about 12. The solution was cooled to about 20 C.;57.6 g. (0.20 moles) of tetraethyl methylenediphosphonate was addedslowly. After stirring for about minutes, the aqueous electrolytesolution was extracted with Cl-lCl lCCl (about 3: l and the organicphase separated. After removal of the solvents from the organic phase, aP nmr spectrum indicated that about 95 percent of the residue wastetraethyl dichloromethylenediphosphonate. The product weight wasapproximately 66 g.

As noted above, the halogenated tetramethyl and tetraethylmethylenediphosphonate compounds prepared according to the presentinvention can be converted to their corresponding water soluble salts,in which form they are valuable as detergency builders. Thewater-soluble salts especially useful are the alkali metal (sodium,potassium) ammonium or substituted ammonium fomis. Conversion of theesters described herein can be readily performed by an ordinaryhydrolysis and neutralization with a suitable base, e.g., sodiumhydroxide. The water-soluble salts of the halogenatedmethylenediphosphonates are useful as builders with a wide variety oforganic synthetic detergents including anionic, nonionic. ampholytic andzwitterionic detergents.

EXAMPLE Vll Tributyl Dibromophosphonoacetate Tributyl phosphonoacetate,17.2 g. (0.053 mole) is added to a 2-liter flask containing a two phasesystem of water, 4.5 percent NaBr, and carbon tetrachloride. 0.098 mole(about 10 percent excess) of NaOBr in water is then added slowly withstirring. The mixture is further reacted for 10 minutes at 0 to 5 C.,and then allowed to separate into layers. The car-Methylenediphosphonate or phosphonoacetate Hypohallte reactant reactantReaction products Diruethyl dlethyl KOI Diethyl dirnethyldliodoligathytlenediphosmethylenediphosphonate. p one e.

Chloromethyl 2- NaO C1 Chloromethyl 2-chloroethyl chloroethyl dlmethyldimethyl dic111oromethylenediphosmethylene-diphosphonate. phonate.

Diisopropyl propyl NaOBr Dlisopropyl propyl phosphonoacetate.dibromo-phosphono- Tri(dlfluoromethy1) KOBr Trl(difluoromethyDil-bromq2-br0moethy1 ethyl dlbromomethylmethylene enedlphosphonate.diphosphonate.

Tri(2-isobutyl) phos- NaOI Iri(2-1s0butyl) dllodophosphonoacetate.phonoaeetates.

3-chl0r0propeny1 2- Ca(0C1) 3-ch10r0propenyl 2-bromobromopentenylpentenyl 2-iodobutenyl 2-lodo-buteny1 dichlorophosphonophosphonoacetate.acetate.

'Irlpropyl monochloro- NaOBr 'lripropyl monobromomonophosphonoacetate.chlorophosphonoaeetate. Triethyl monobromo- NaOI Triethylmonobromomonophosphonoacetate. lodophosphonoacetate.

Tributyl phospbono- Liquid Tributyl dibromophosacetate. bromine]phonoacetate.

NaOH.

Tripropenyl phospho- Ca(OBr) Tripropenyl dibromophosnoacetate.phonoacetate.

EXAMPLE V111 Triethyl Dibromophosphonoacetate One mole 226.0) grams oftriethyl phosphonacetate is placed in a reaction flask with 4 moles160.0 grams) NaOH in H 0 and 500 grams of Na SO. at 0 C. and stirredvigorously. Two moles (320.0 grams) Br are then dripped into thetwophase system. After the Br has been added the mixture is stirred for10 minutes more at 0 C. At this time the layers are separated and the H0 layer extracted three times with CCl,. The CCl, layer is dried overanhydrous sodium sulfate for several minutes then filtered and thesolvent removed by evaporation. The product, triethyldibromophosphonoacetate, E is obtained in -100 percent yield and ispercent pure.

EXAMPLE 1X Triethyl Dichlorophosphonoacetate One mole (226 grams) oftriethyl phosphonoacetate is placed in a reaction flask with four molesgrams) of NaOH and 500 grams of potassium carbonate in H O at 0 C. andvigorously stirred. Two moles (142.0 grams) Cl are then bubbled into thetwo-phase system. After the chlorine has been added, the mixture isstirred for 10 minutes more at 0 C. i At this time the layers areseparated and the water layer is ex- :tracted five times with CCl TheCCl, layer is dried over anlhydrous sodium sulfate for several minutes,then filtered and the CCl, is removed by evaporation. The product,triethyl dichlorophosphonoacetate, is obtained in 80-100 percent yieldand is 90 percent pure.

EXAMPLE X product layer and dried over anhydrous sodium sulfate forminutes, then filtered and the solvent removed by evaporation. Theproduct, triethyl monobromophosphonoacetate, is obtained in 80-100percent yield and is =60 percent pure.

EXAMPLE Xl Triethyl Monochlorophosphonoacetate One mole (226.0 grams) oftriethyl phosphonoacetate is placed in a reaction flask and cooled to 0C. and stirred vigorously as l mole of NaOCl is added slowly in H 0solution containing 150 grams of Na CO After addition is complete, themixture is stirred for an additional minutes. At this time the layersare separated and the water layer rinsed with CCl The CC] rinse iscombined with the original product layer and dried over anhydrous sodiumsulfate for minutes, then filtered and the solvent removed byevaporation. The product, triethyl monochlorophosphonoacetate, isobtained in 80-100 percent yield and is -60 percent pure.

When, in the above example, the following compounds listed in column 1are substituted for the triethylphosphonoacetate on a molar basis andthe compounds listed in column 2 are substituted for the NaOCl on amolar basis, substantially equivalent results are obtained in that thecompounds listed in column 3 are formed in good yield.

Methylenediphosphonate or phosphonoacetate Hypohalite The dibromoanddiiodo-methylenediphosphonates disclosed in examples l-Xl are effectiveextreme pressure additives when used at the 5 percent level in e.g., aKendall base SAE mineral oil. They are more effective than thecorresponding dichloromethylenediphosphonate esters.

It is to be understood that within the broad ranges set forthhereinbefore and in the claims, one skilled in the art can readilyoptimize the conditions for any particular halogenatedmethylenediphosphonate or phosphonoacetate desired. it is also to beunderstood that at the extreme limits of the described ranges,insignificant amounts of product may be obtained; however, as explainedabove one skilled in the art can readily optimize the conditions for anyone halogenated methylenediphosphonate or phosphonoacetate derivative.

What is claimed is: l. A process which comprises the steps of reacting,with vigorous stirring, a compound selected from the group consisting of(l) methylenediphosphonates having the formula ll Po CliPO R in whicheach R is selected from the group consisting of methyl, ethyl,halomethyl and haloethyl radicals and (2) phosphonoacetates having theformula R 'l 'o CH,COOR in which each R is selected from the groupconsisting of alkyl, alkenyl, haloalkyl, and haloalkenyl radicalscontaining from two to four carbon atoms with a hypohalite ion selectedfrom the group consisting of OCl, OBr' or 01',

the molar proportions of the reactants corresponding to one mole of saidester reactant to from about 0.75 to about 6.0 moles of said hypohaliteion,

in a two-phase reaction mixture comprised of an aqueous' phasecontaining from 4 to about 65 percent electrolyte, by weight and aninert water-immiscible organic solvent phase in which the halogenatedmethylenediphosphonates and halogenated phosphonoacetates formed in thereaction are soluble to at least 5 percent by weight,

the temperature of the reaction being in the range of from 0 to 75 C.,the pH of the aqueous solution being greater than about 7,

and the reaction time being from about I minute to about 2 hours. 2. Theprocess of claim 1 wherein (a) the methylenediphosphonate orphosphonoacetate and (b) the hypohalite ion are present in a molar ratioof about l:0.75 to about 1:1.10.

3. The process of claim 2 wherein (a) the methylenediphosphonate orphosphonoacetate and (b) the hypohalite ion are present in a molar ratioof about 110.95 to about l:l.l0 and wherein the aqueous electrolytesolution contains from about 15 to about 65 percent electrolyte byweight.

4. The process of claim 3 wherein the inert organic solvent is selectedfrom the group consisting of carbon tetrachloride, chloroform andsym-tetrachloroethane.

5. The process of claim 4 wherein the pH is above 1 l.

6. The process of claim 2 wherein each mole of methylenediphosphonate orphosphonoacetate is reacted with from about 2.0 to about 6.0 moles of ahypohalite ion.

7. The process of claim 8 wherein the amount of hypohalite is from about2.05 to about 2.] moles.

8. The process of claim 7 wherein the inert organic solvent is selectedfrom the group consisting of carbon tetrachloride, chlorofonn, andsym-tetrachloroethane.

9. The process of claim 8 wherein the pH is above 1 l.

10. The process of claim 1 wherein each R is methyl and the aqueoussolution contains a: least 15 p ercent electrolyte.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Rs.,525,188 Dated November 30, 1971 Invenggr(3) J'Ohh Downing Curry It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

olumn 3, line 26, before "diiodophosphonoacetate" insertdichlorophosphonoacetate, triethyl dibromophosphonoacetate, triethylColumn 5, line 39, delete "K0" and insert therefor KOH Column 5, line 75to Column 6, line 1, after "phosphonoacetate" at Column 5, line 75delete "or the methylenediphosphonate or phosphonoacetate" Column 7,line 46, delete "R PO CXPO R and insert therefor Column 8, line 18,after "maintained" and before "about" insert Column 8, line 47, delete"monoido-" and insert therefor monoiod Column 12, line 9, delete "R P0CHPO R and insert therefor R P0 11 F0 1? Signed and sealed this 18th dayof July' 1 972.

(SEAL) t: L Attes m EDWARD M.FLETCHER JR. ROBERT- GOTTSCHALK AttestingOfficer Commissioner of Patents

2. The process of claim 1 wherein (a) the methylenediphosphonate orphosphonoacetate and (b) the hypohalite ion are present in a molar ratioof about 1:0.75 to about 1:1.10.
 3. The process of claim 2 wherein (a)the methylenediphosphonate or phosphonoacetate and (b) the hypohaliteion are present in a molar ratio of about 1:0.95 to about 1:1.10 andwherein the aqueous electrolyte solution contains from about 15 to about65 percent electrolyte by weight.
 4. The process of claim 3 wherein theinert organic solvent is selected from the group consisting of carbontetrachloride, chloroform and sym-tetrachloroethane.
 5. The process ofclaim 4 wherein the pH is above
 11. 6. The process of claim 2 whereineach mole of methylenediphosphonate or phosphonoacetate is reacted withfrom about 2.0 to about 6.0 moles of a hypohalite ion.
 7. The process ofclaim 8 wherein the amount of hypohalite is from about 2.05 to about 2.1moles.
 8. The process of claim 7 wherein the inert organic solvent isselected from the group consisting of carbon tetrachloride, chloroform,and sym-tetrachloroethane.
 9. The process of claim 8 wherein the pH isabove
 11. 10. The process of claim 1 wherein each R is methyl and theaqueous solution contains at least 15 percent electrolyte.